How do you do a jig-saw puzzle of 27,000 pieces? In three dimensions?
That's the task a handful of archaeologists in Germany have just completed. It took them nine years, with all the pieces laid out in a room the size of a football field.
They claim to have enjoyed it.
The pieces were the shards of 3,000-year-old sculptures, smashed to smithereens as a result of the British bombing of Berlin in November 1943.
The result - 60 fantastical figures of people, scorpions, lions and birds - now stands in a series of rooms in the city's Pergamon Museum.
Before the war they were the private collection of Max Freiherr von Oppenheim, a member of the banking dynasty, and so rich beyond imagination.
He worked as a diplomat in Cairo, wandering the Middle East to keep his eye on the British who were also keen on a bit of empire-building in the region.
But he was also an archaeologist - a romantic figure comparable to Hollywood's Indiana Jones - and in 1899, near where the Berlin to Baghdad railway was being constructed, he came across the palace of an Aramaean king in what would now be north-east Syria, near the Turkish border.
He sought permission to excavate the site, known as Tell Halaf, between 1911 and 1913. Work started and then stopped because of World War I, but was completed in 1927.
What emerged were the stunning statues of gods and animals, sculpted in basalt.
The finds were divided between the national museum in Aleppo and Oppenheim himself, who took his share home to Berlin, where he created a private museum in an old iron-foundry.
The great British crime writer, Agatha Christie, was one of those who flocked to visit.
She later remembered being shown around by Oppenheim during which he stopped and suddenly stroked the huge statue of a woman on a throne. Oppenheim purred: "Ah, my beautiful Venus".
The peace and love ended in those raids in 1943. The wood of the ancient works of art was destroyed in the intense heat of the blaze and the stone cracked and shattered when fire hoses doused the flames.
Oppenheim was heart-broken and had the rubble collected in the hope of re-assembly.
He said: "It would be truly wonderful if the smashed fragments from the stone images could somehow be gathered together, brought to the National Museums and reassembled at a later date.
"In the case of this collection, it would, however, be a tremendous task, since the sculptures have been shattered into countless, often minute fragments".
He died three years later, without that dream being realised.
No 'easy way'
Nothing then happened for the duration of the Cold War. The rubble was in the East, in the Pergamon Museum, and the people trying to fulfil Oppenheim's wishes were in the West.
Only a decade after the fall of the Berlin Wall was the project started. A team of four people laid out an estimated 27,000 bits on 300 wooden palettes.
There was no easy way. No magical computer programme to do it. Rather, they had to get down on their knees and examine each piece (just like you would a jigsaw puzzle).
They worked from Oppenheim's own photographs "with our eyes and brain", as one of the archaeologists, Dr Lutz Martin, explained to the BBC. "And for such a mass of fragments, it was the best solution".
But wasn't it boring? "No, no! It was so satisfying. Every day you have a result. If you sit in the office you write a paper and it's no good, but with this you would get a result every day."
First, they would look for recognisable bits from the surface of sculptures. The interiors were much harder. After the laborious fitting together, they were finished in 2008. Then the restorer took a year to stick the bits together.
In the exhibition in the Pergamon Museum in Berlin, you can see the joins, but there is still a great awe and majesty to the works.
For the archaeologists, the task is over. They wander the exhibition, basking in the satisfaction of their work.
Dr Nadja Cholidis told the BBC that her great pleasure was to have fulfilled the wish of a man you sense she would have loved to have met: "I always think about what Max von Oppenheim would say now that his dream has come true.
"When the last piece was done, I was overwhelmed that it is now 2011, and we were able to fulfil his wishes and his dream".